1. Field of the Invention
The present invention relates to a wind power generating device having a cooling structure.
2. Description of Related Art
In a general wind power generating device, it is required to maintain the reliability of the device by efficiently dissipating heat generated in an electric power generator of the device to the outside and by decreasing temperature of the generator (or internal temperature of the device) to a prescribed allowable temperature or below. Therefore, in a conventional wind power generating device with a closed generator, an air blower is attached to a horizontal shaft to which a plurality of blades receiving wind power are fixed, outside air is supplied into the wind power generating device through an air supplying opening by using the air blower, and the generator functioning as a heat generating unit is cooled.
A conventional wind power generating device having the above-described cooling structure will be described below as an example. FIG. 30 is a sectional view showing a structure of a conventional wind power generating device disclosed in Published Unexamined Japanese Patent Application S58-65977 (1983), and FIG. 31 is an enlarged sectional view showing principal components of a cooling structure of the conventional wind power generating device shown in FIG. 30. In FIG. 30 and FIG. 31, referential numeral 1 denotes a pole which is vertically arranged in an elevated spot, a wind-strong spot of an island or a cape, an offshore spot with high wind activity or a coastal spot with high wind activity for example. A nacelle 2 is fixed to a top portion of the pole 1. An electric power generator described later is arranged in the nacelle 2. A hub 4 is arranged in a front space (that is, a windward-side space) of the nacelle 2. A plurality of blades 3 are fixed to the hub 4 and extend in a radial direction of the hub 3. The hub 4 is attached to a top portion of a horizontal shaft 6 which functions as a rotational shaft rotating a rotor (not shown) of a closed type generator 5. A step-up gear 7 and a brake 8 are attached to the horizontal shaft 6. The step-up gear 7 accelerates a rotational speed of the blades 3 and transmits the rotational motion of the blades 3 to the rotor. The brake 8 stops the rotation of the horizontal shaft 6. Also, an air blower 9 is attached to a top portion of the horizontal shaft 6. The air blower 9 forcibly ventilates the nacelle 2 to cool the closed type generator 5. An air supplying opening 10 is arranged in a bottom portion of the nacelle 2 placed in the neighborhood of the closed type generator 5, and outside air is supplied in the nacelle 2 through the air supplying opening 10. Also, an exhaust vent 11 is arranged in both a ceiling portion and another bottom portion of the nacelle 2 placed in the neighborhood of the air blower 9, and heat generated in the closed type generator 5 is dissipated to the outside through the exhaust vents 11. As shown in FIG. 31, each exhaust vent 11 is formed in a labyrinth structure, and a heat flow H is exhausted to the outside through the exhaust vents 11.
Because the conventional wind power generating device has the above-described cooling structure, air placed in the nacelle 2 is forcibly ventilated by using the air blower 9 attached to the horizontal shaft 6. Therefore, heat generated in the closed type generator 5 is dissipated to the outside, and this cooling structure can prevent the performance of the conventional wind power generating device from deteriorating due to the heat remaining in the nacelle 2. Also, because the air supplying opening 10 and the exhaust vents 11 have the above-described structure, the intrusion of rain or snow into the nacelle 2 can be prevented when rain or snow falls. Therefore, it is generally said that the structure of the air supplying opening 10 and the exhaust vents 11 can prevent the units placed in the nacelle 2 from being corroded.
There has been increasing demand in recent years for wind power generation due to the fact that large amounts of clean energy can be obtained by wind power generation. Therefore, this demand for wind power generation has lead to demand for wind power generation with a high output power, a high efficiency and a superior maintenance performance.
However, because the conventional wind power generating device has the above-described cooling structure, a part of the driving power obtained from the wind power in the blades 3 is consumed by the air blower. Therefore, there is a problem that an energy generation efficiency is lowered in the conventional wind power generating device.
Also, in the conventional wind power generating device having the above-described cooling structure, even though the structure of the air supplying opening 10 and exhaust vents 11 is skillfully designed, it is difficult to remove water and/or salt contained in the outside air, and the outside air containing water and/or salt is undesirably supplied into the nacelle 2. Therefore, it is difficult to completely prevent the units placed in the nacelle 2 from being corroded by the water and/or salt contained in the outside air, and there is a problem that corrosion treatment is required for the units other than the closed type generator 5.
In addition, in the conventional wind power generating device having the above-described cooling structure, in cases where a filter is arranged in the air supplying opening 10 to remove water and/or salt from the outside air supplied into the nacelle 2, maintenance working such as filter exchange is additionally required. Also, because each exhaust vent 11 is formed in the labyrinth structure, there is another problem that the structure of the nacelle 2 is complicated.
An object of the present invention is to provide, with due consideration to the problems of the conventional wind power generating device having the above-described cooling structure, a wind power generating device with a simple cooling structure in which an inside temperature is reliably maintained to a value equal to or lower than a standard value.
The object is achieved by the provision of a wind power generating device comprising a horizontal shaft arranged on a top portion of a pole vertically arranged so as to be directed to a windward side, a generator having both a rotor fixed on a leeward side of the horizontal shaft and a stator arranged on the outside of the rotor, a blade which is fixed to the horizontal shaft on the windward side of the horizontal shaft and is rotated by a wind power, and a cylindrical frame which separates the stator of the generator from outside air and has a heat dissipating function to dissipate heat, which is generated in the generator according to the rotation of the rotor of the generator, to the wind which gives a rotational force to the rotor through the blade.
In the above configuration, the heat generated in the generator is transferred to the cylindrical frame by conduction. Also, wind in the outside air, which has already given a rotational force to the rotor through the blade, collides with the cylindrical frame and flows along the cylindrical frame, and heat is dissipated from the cylindrical frame to the outside air.
Accordingly, a heat dissipating performance of the heat generated in the generator to outside air can be improved. Therefore, a temperature of units and the generator arranged in the wind power generating device can be reliably maintained to a value equal to or lower than a standard value.
Also, the wind power generating device does not have an air supplying opening, an exhaust vent or an air blower used in the prior art. The wind power generating device having the simple structure can be manufactured.
Also, because the heat generated in the generator is dissipated to the outside air which has already given a rotational force to the rotor through the blade, the driving power obtained from the wind power is not consumed for the cooling of the generator. Therefore, a high heat dissipating coefficient can be obtained, and the energy generation efficiency can be improved in the wind power generating device.
It is preferred that the heat dissipating function of the cylindrical frame is exerted by a fin which is outwardly arranged on the cylindrical frame in a radial direction of the cylindrical frame and extends in an axial direction of the cylindrical frame.
Therefore, because the fin is arranged on the cylindrical frame, a heat dissipating area, from which the heat is dissipated to outside air, can be increased, and a cooling performance for the generator can be considerably improved as compared with a case where no fin is arranged on the cylindrical frame.
It is also preferred that an angle between an extending direction of a front portion of the fin on the windward side and a rotational direction of the blade is set to an acute angle.
Therefore, in addition to the effect of the increase of the heat dissipating area, because a flow speed loss of the outside air at an inlet of the fin can be decreased, a flow rate of the outside air can be increased. Also, because the outside air having a motion component directed in a circle-circumferential direction of the wind power generating device (or a rotational direction of the blade) flows along side surfaces of the fin, a heat transfer coefficient from the outer surface of the fin to the outside air can be heightened, and the cooling performance for the generator can be improved.
It is also preferred that the fin is composed of a plurality of divided fins serially arranged in the axial direction of the cylindrical frame, and each pair of divided fins adjacent to each other are arranged at positions different from each other along a circle-circumferential direction of the cylindrical frame.
Therefore, in addition to the effect of the increase of the heat dissipating area, a plurality of areas, at which a heat transfer coefficient is heightened according to a boundary layer renewing effect, can be obtained along the flow direction of the outside air, and a high cooling performance for the generator can be obtained.
It is also preferred that an angle between an extending direction of the divided fin arranged on the windward side and a rotational direction of the blade is set to an acute angle.
Therefore, in addition to the effect of the increase of the heat dissipating area, because the outside air collides with one side surface of each divided fin following the divided fin arranged on the windward side, a boundary layer of the outside air becomes thinner, a plurality of areas, at which a heat transfer coefficient is heightened according to a boundary layer renewing effect, can be obtained in a wide region of the side surfaces of the divided fins. Therefore, the cooling performance for the generator can be improved.
It is also preferred that the wind power generating device further comprises a windward-side clamper arranged on the windward side of the cylindrical frame, and a leeward-side clamper arranged on the leeward side of cylindrical frame to put the stator of the generator between the windward-side clamper and the leeward-side clamper, wherein the height of an upper surface of the windward-side clamper is the same as that of an outer peripheral surface of the cylindrical frame, and the height of the fin is higher than that of an upper surface of the leeward-side clamper in the axial direction of the cylindrical frame.
Therefore, because the heat dissipating performance can be improved on the leeward side of the fin, a superior heat dissipating performance can be obtained along the whole upper and side surfaces of the fin, and a high cooling performance for the generator can be sufficiently obtained.
It is also preferred that the wind power generating device further comprises a windward-side clamper arranged on the windward side of the cylindrical frame, and a leeward-side clamper arranged on the leeward side of cylindrical frame to put the stator of the generator between the windward-side clamper and the leeward-side clamper, wherein an upper surface of the windward-side clamper and an outer peripheral surface of the cylindrical frame have the same height as that of an upper surface of the leeward-side clamper in the axial direction of the cylindrical frame.
Therefore, because the flow of the outside air passes along the fin without decreasing the flow speed, the whole upper and side surfaces of the fin function as a superior heat dissipating plane, and a high cooling performance for the generator can be sufficiently obtained.
It is also preferred that the wind power generating device further comprises a windward-side clamper arranged on the windward side of the cylindrical frame, and a leeward-side clamper arranged on the leeward side of cylindrical frame to put the stator of the generator between the windward-side clamper and the leeward-side clamper, wherein the height of an upper surface of the windward-side clamper and the height of an upper surface of the leeward-side clamper are higher than that of an outer peripheral surface of the cylindrical frame in the axial direction of the cylindrical frame, and the height of the fin is higher than the height of an upper surface of the windward-side clamper and the height of an upper surface of the leeward-side clamper in the axial direction of the cylindrical frame.
Therefore, because the outside air directly collides with surfaces of the fin placed at a position higher than that of the cylindrical frame, a high heat transfer coefficient can be obtained. Also, because the outside air directly colliding with the surfaces of the fin does not collide with the leeward-side clamper, the whole surface of the fin functions as a superior heat dissipating plane, and a high cooling performance for the generator can be sufficiently obtained.
It is also preferred that the heat dissipating function of the cylindrical frame is exerted by a plurality of projections (or pins) which is outwardly arranged on the cylindrical frame in a radial direction of the cylindrical frame.
Therefore, because the projections (or the pins) are outwardly arranged on the cylindrical frame, in addition to the effect of the increase of the heat dissipating area, a plurality of areas, at which a heat transfer coefficient is heightened according to a boundary layer renewing effect, can be obtained along the flow direction of the outside air. Also, because vortexes of an air flow are generated on the leeward side of the projections, a turbulence intensity of the outside air flowing along the projections following the front projection placed on the windward side is increased, the heat transfer coefficient for the projections placed on the leeward side is heightened, and a high cooling performance for the generator can be obtained.
It is also preferred that the heat dissipating function of the cylindrical frame is exerted by a plurality of fins arranged at short pitches on an upper region of the cylindrical frame, in which influence of solar radiation is received, or on a lower region of the cylindrical frame in which influence of the pole is received, and each fin is outwardly protruded from the cylindrical frame in a radial direction of the cylindrical frame and extends in an axial direction of the cylindrical frame.
Therefore, a high cooling performance for the generator can be obtained, a distribution of the temperature of the engine in the circle-circumferential direction of the wind power generating device (or the rotational direction of the blade) can be arbitrarily set.
It is also preferred that the heat dissipating function of the cylindrical frame is exerted by a plurality of fins which are arranged on the cylindrical frame at various heights, and each fin is outwardly protruded from the cylindrical frame in a radial direction of the cylindrical frame and extends in an axial direction of the cylindrical frame.
Therefore, a high cooling performance for the generator can be obtained, a distribution of the temperature of the engine in the circle-circumferential direction of the wind power generating device (or the rotational direction of the blade) can be arbitrarily set.
It is also preferred that the heat dissipating function of the cylindrical frame is exerted by an outer circumferential wall extending in a circle-circumferential direction of the cylindrical frame.
Therefore, a heat dissipating area can be increased. Also, an ascending air current grows, and the heat dissipation is promoted by natural convection. Therefore, a cooling performance for the generator can be improved.
The object is also achieved by the provision of a wind power generating device comprising a horizontal shaft arranged on a top portion of a pole vertically arranged so as to be directed to a windward side, a generator having both a rotor fixed on a leeward side of the horizontal shaft and a stator arranged on the outside of the rotor, a blade which is fixed to the horizontal shaft on the windward side of the horizontal shaft and is rotated by a wind power, a cylindrical frame separating the stator of the generator from outside air, and a cover, with which the cylindrical frame is covered, for leading the wind, which gives a rotational force to the rotor of the generator through the blade, to a space placed in the neighborhood of the cylindrical frame.
In the above configuration, heat generated in the generator is transferred to the cylindrical frame by conduction. Also, the wind of outside air, which has already given a rotational force to the rotor through the blade, passes through an area between the cylindrical frame and the cover, and the heat is dissipated from the cylindrical frame to the outside air.
Accordingly, a flow speed of the outside air is increased on an outer peripheral surface of the frame, and the cooling performance for the generator can be improved. Also, because the cover prevents the outer peripheral surface of the frame from directly receiving solar radiation, the increase of the temperature of the generator due to direct solar radiation can be suppressed, and a wind power generating device with superior cooling performance can be obtained.
It is preferred that a clearance between the cylindrical frame and the cover is gradually shortened in a windward range from a front portion of the cover on the windward side to a portion of the cover placed in the neighborhood of the cylindrical frame.
Therefore, the flow speed of the outside air can be increased in the neighborhood of the outer peripheral surface of the frame, and a sufficient cooling performance for the generator can be obtained.
It is also preferred that a clearance between the cylindrical frame and the cover is gradually lengthened in a leeward range from a portion of the cover placed in the neighborhood of the cylindrical frame to a rear portion of the cover on the leeward side.
In this case, because an open area at the outlet of the outside air can be increased, a flow speed of the outside air can be decreased at the outlet, a pressure loss at the outlet of the cover is reduced, and the flow speed of the outside air passing along the outer peripheral surface of the frame is increased. Therefore, a sufficient cooling performance for the generator can be obtained.
It is also preferred that the wind power generating device further comprises a windward-side clamper arranged on the windward side of the cylindrical frame, and a leeward-side clamper arranged on the leeward side of cylindrical frame to put the stator of the generator between the windward-side clamper and the leeward-side clamper, wherein an upper surface of the windward-side clamper and an outer peripheral surface of the cylindrical frame have the same height as that of an upper surface of the leeward-side clamper in the axial direction of the cylindrical frame.
Therefore, the outside air can smoothly pass through the area between the cover and the frame without decreasing the flow speed of the outside air.
It is also preferred that the wind power generating device further comprises a plurality of supporting bars (or fins), which are outwardly arranged on the cylindrical frame in a radial direction of the cylindrical frame and extend in an axial direction of the cylindrical frame, for supporting the cover by attaching the cover to a top portion of the supporting bars.
Therefore, the speed of the outside air flowing into a duct-shaped space, which is surrounded by the cover, the frame and the supporting bars (or the fins) adjacent to each other, can be increased. Also, because inner and outer peripheral surfaces of the cover, which is integrally formed with the supporting bars, can function as a heat dissipating plane, a sufficient cooling performance for the generator can be obtained.
It is also preferred that the wind power generating device further comprises a windward-side clamper arranged on the windward side of the cylindrical frame, and a leeward-side clamper arranged on the leeward side of cylindrical frame to put the stator of the generator between the windward-side clamper and the leeward-side clamper, wherein the height of an upper surface of the windward-side clamper and the height of an outer peripheral surface of the cylindrical frame are higher than that of an upper surface of the leeward-side clamper in the axial direction of the cylindrical frame.
Therefore, because the outside air flowing into the area between the cover and the frame is accelerated and collides with the leeward-side clamper, the heat dissipation from the cover, the frame and the leeward-side clamper can be promoted, and a sufficient cooling performance for the generator can be obtained.
It is also preferred that the wind power generating device further comprises a supporting bar (or a fin), which is outwardly arranged on the cylindrical frame in a radial direction of the cylindrical frame and extends in an axial direction of the cylindrical frame, for supporting the cover.
Therefore, the heat dissipation from the supporting bar (or the fin) can be promoted, and a sufficient cooling performance for the generator can be obtained.
It is also preferred that the cover is arranged on an upper region of the cylindrical frame, in which influence of solar radiation is received, or on a lower region of the cylindrical frame in which influence of the pole is received.
Therefore, the increase of the heat load in the upper region of the cylindrical frame can be suppressed, the heat dissipating performance in the lower region of the cylindrical frame can be improved, and a sufficient cooling performance for the generator can be obtained.